Recent Developments in Lead‐Free Double Perovskites: Structure, Doping, and Applications

Abstract

Lead-free perovskite structures have been recently attracting considerable attention because of their eco-friendly nature and properties, such as their lead-based structure. In this work, we reviewed the lead-free doublep erovskite (LFDP) structure because of its unique electronic dimensions, chemical stability,a nd substitutionalc hemistry compared with other lead-free structures. We highlighted the recent progress on crystal structure prediction, synthesis methods, metal dopants, and ligand passivationo nL FDPs. LFDPs are useful for severala pplications,s uch as solar cells, light-emitting diodes, degradation of photocatalytic dyes, sensors, and X-ray detectors. This report provides as ummary of recent progress as ar eference for further research on lead-freep erovskite structures.The ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.

Lead-Free Metal Halide Perovskites for Hydrogen Evolution from Aqueous Solutions

“…Beyond the earlier mentioned MHPs, double ones have been also reported in literature [57,60,61]. They can have the general formula A 2 B'B"X 6 in which A is a monovalent cation, B' and B" are a pair of heterovalent (i.e., monovalent and trivalent) metal cations to give an average +2 valence state (e.g., Ag + and Bi 3+ ), while X is a halide [60][61][62]. These kind of perovskite derivatives provide an avenue for easy substitution and incorporation of metal cation in B'-and B"-site, the possibility to use various organic or inorganic species in the A-site and a variation of the halide composition in the X-site [60].…”

“…Double perovskites have been synthesized since the 1970s, however, only a few types of them have been applied so far in solar cells [57,60,62]. In particular, the most popular double perovskite used in PV applications is the inorganic Pb-free Cs 2 AgBiBr 6 which is characterized by properties similar to those of the typical MAPbI 3 and MAPbBr 3 3D MHP (e.g., high defect tolerance) [57].…”

“…It has an indirect band gap of about 2.0 eV and good moisture as well as thermal stability. Its structural network is ideally composed of corner shared octahedra, alternately formed by the Ag + and Bi 3+ metal cations with the Br − anions and inorganic Cs + ions that occupy the generated octahedral cavities [60][61][62]. Due to the good stability as to the optoelectronic properties, nowadays Cs 2 AgBiBr 6 perovskite has been also investigated for the photocatalytic H 2 generation from aqueous solutions [30,32].…”

Lead‐Free Double Perovskite Cs2AgInCl6

“…[6] Anewly developed strategy to address the Pb toxicity issue is to replace every two Pb 2+ cations with one monovalent cation and one trivalent cation, forming the charge-ordered double perovskite with the general formula A 2 B I B III X 6 . [7] Notably,a mong the various compositions with double perovskite structure,Cs 2 AgInCl 6 has received the most attention because of its direct band gap character,long carrier lifetimes, and easy solution processability.Since the pioneering work on Cs 2 AgInCl 6 in 2017 reported by Giustino et al [8] and Zhou et al [9] nearly simultaneously,many efforts have been devoted to its synthesis,m odification of its composition, study of its electronic structure,o ptoelectronic properties,and applications.…”

Reducing Agents for Improving the Stability of Sn‐based Perovskite Solar Cells

“…To achieve this objective, a straightforward idea is to substitute Pb 2+ with other cations. For example, replacement of Pb 2+ with one monovalent cation and one trivalent cation to construct a double perovskite structure . Moreover, several divalent cations, such as Sn 2+ , Ge 2+ and Cu 2+ are also promising for Pb 2+ substitution .…”